Smart Sensor CAN Node

Created: May 17, 2016

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Description

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Summary

The advancement in data communications has created efficient methods for several devices to communicate over a minimum number of system wires. The Controller Area Network (CAN) is one of these methods. It sends and receives messages over a two-wire CAN bus. The nodes broadcast their individual messages over the CAN bus. Meanwhile, the receivers are set up to accept the message and anticipate an Acknowledgment (ACK) signal, indicating the receipt of a non-corrupted message. The device uses the MCP2515 CAN controller of Microchip, which is a stand-alone controller that implements CAN specification version 2.0B. It is capable of transmitting and receiving both standard and extended data and remote frames. In addition, it reduces the host microcontroller’s overhead with its two acceptance masks and six acceptance filters.

This CAN-NET Node board is composed of hardware devices that are used in conjunction with software programming methods to optimize the CAN. The MCP2515 CAN controller is the heart of the CAN interface. It handles all of the transmitting and receiving of message packets that contain useful information for other nodes on the network via the CAN bus. The MCP2515 CAN controller is also designed to interface with the Serial Peripheral Interface (SPI) port. The SPI port is available on the PIC16F876 microcontroller, and the MCP3201 Analog-to-Digital Converter. The PIC16F876 microcontroller stores the program in memory and reads the DIP switch settings for sending and receiving messages. It controls the PWM output and enables the MPLAB ICD to be used as a debugging tool.

The bus configuration operates by the multi-master principle, and allows several node boards to connect directly to the bus. If one node board fails in the system, the other node boards are not affected which is the common problem of ring type networks. An advantage in utilizing this type of system is the ability to monitor several node boards at any given time. It does not only monitor several devices but also replaces a large wiring harness.